English Grammar – When to Use Commas
The comma is perhaps the most over-used punctuation mark in the English language. Knowing when to use them in a sentence can be daunting. If you’re feeling confused, don’t worry – following these basic rules will make it easier for you to determine how and when to use commas appropriately.
When you have three or more elements in a series, you need to use commas to separate them. Make sure you use a comma after the “and” in the series so things will be clear when you have numerous things to mention in a sentence. An example of this would be “Tom, Mary, George, Ben, and Henry will all be going to the ballgame.” See how clear things are when you use commas after each name and before the “and” in the sentence? The comma before “and” is known as the Oxford or serial comma.
To make introductory elements less confusing in your sentences, you can use commas to separate them from the rest of the sentence. An example of this would be, “Skating toward home, Ryan realized he forgot his helmet at school.” If a sentence isn’t confusing without the comma, you can leave it out, but when in doubt use the comma.
“And,” “for,” “but,” and “so” are all conjunctions that can be used with a comma in a sentence to connect independent clauses. Use these combinations in sentences like, “Angel went to town for some bread, but when she got there she realized she forgot her money at home.” Both halves of the sentence could stand on their own as sentences, so it’s necessary to use the comma to combine them into one sentence.
You’ll also use commas to separate parenthetical elements. These are clauses in a sentence that, if removed, would not affect the sentence at all – they’re just additional information added to the sentence. A sentence such as, “The Eastbrook Library, which is on the east side of town, is a good place to do genealogy research.” In this case, the phrase, “which is on the east side of town,” is a parenthetical element.
A good way to decide whether or not a sentence contains a parenthetical element, and to decide whether it requires commas or not, is to read the sentence without the element in it. If the sentence still makes sense, you’re looking at a parenthetical element. In the previous example, the sentence would read like, “The Eastbrook Library is a good place to do genealogy research,” which does make sense without the element, “which is on the east side of town.”
In addition, commas are typically used to separate adjectives that coordinate. If you can use “and” or “but” in a sentence to separate adjectives, then you could also use a comma in place of them in a sentence. For example, you can see this in the sentence, “She is a very bright and educated woman.” In this case, you can leave out the “and” in this sentence and write the sentence as, “She is a very bright, educated woman.”
Clearly, there are many uses for commas in a sentence. You can even use them to create dramatic pauses in your sentences. Just be careful of overdoing it. If you aren’t sure if your sentence needs a comma or not, try writing it both ways and check to see if it follows any of the above rules.